Telephone system



Sept. 10, 1935. A. E. HAGUE ET AL. 19,595

TELEPHONE SYSTEM Original Filed July 1, 1932 3 Sheets-Sheet 1 FIG 4 A.. HAGUE INVENTORS JADRAPER ATT RNE Sept. 10, 1935. A. E. HAGUE El AL TELEPHONE SYSTEM Original Filed July 1, 1952 3 Sheets-Sheet 2 FIG. 2

AE. HAGUE ,m/vzxvrons Jab/MP5,?

AT ORNE Sept. 10, 1935. A. E. HAGUE ET AL 19,695

' TELEPHONE SYSTEM Original Filed July 1, 1932 5 Sheets-Sheet 3 21:11 FEM-H'- D/ZL TONE

, AE. HAGUE HWENTORS By (/W FIG. 3

A T ORNE Reissued Sept. 10, 1935 UNITED STATES PATENT OFFICE TELEPHONE SYSTEM Original No. 1,941,085, dated December 26. 1933, Serial No. 620,408, July 1, 1932. Application for reissue June 12, 1935, Serial No. 26,204

10 Claims.

This invention relates to telephone systems and particularly to improvements in automatic te1ephone systems.

An object of this invention is to increase the 5 utility of the switching facilities in automatic telephone systems.

Heretofore, in establishing a connection between two subscribers by means of automatic switches, when the calling subscriber has failed to actuate said switches either by failing to dial within a certain time after the seizing of the switches or has failed to complete the desired connection by failure to dial the complete number, a signal has been actuated at an operators position to permit this operator to clear the corn nection either by communicating with the calling subscriber or releasing the switches used in the attempt to establish the connection.

Arrangements have also been provided in which the timing device is connected up to a set of switches seized by a calling subscriber re-- moving his receiver from the switchhook and begins to function so that if the subscriber fails to dial said timing device causes the said seizure of a set of switches to become ineffective and causes the release of a relay which thereby prevents the calling subscriber from seizing another set of switches for dialing as long as his receiver remains off the switchhook.

Other arrangements have been provided in which the timing device is connected up to a set of switches seized, but does not begin to function until some time after said seizure. The arrangement is such that if the subscriber fails to dial within a certain interval after the timing device has started to function a relay is operated to release the seized set of switches and to prevent the calling subscriber from seizing another set of switches for dialing so long as the receiver remains ofi the switchhook.

It is a feature of the present invention to release the automatic switches seized by the calling subscriber when he removes his receiver ofi the switchhook preliminary to the dialing of the wanted subscribers number, if the calling subscriber fails to dial within a certain time after the seizure of the switches or if the subscriber fails to dial the complete number.

It is a feature of the present invention to provide in systems of this kind. a timing device which is connected up to a set of switches seized by a calling subscriber and begins to function immediately so that if the subscriber fails to dial or dialing is not completed within a certain interval, a relay is operated in the line circuit of the calling subscriber to release said set of switches and prevent the calling subscriber from seizing another set of switches for dial ng until after he has replaced the receiver on the switchhock.

Another feature is a timing device common to a plurality of switches for controlling the release of seized switches.

Another feature of this invention is a circuit arrangement whereby if the calling subscriber has hung up his receiver after the completion of a conversation with a called subscriber all of the switches used in the connection are released and if the called subscriber still has his receiver off the switchhook his line will then immediately seize a set of switches, but these switches are released a certain time interval thereafter provided the called subscriber takes no further action within this interval towards the establishing of a new connection and the called subscriber is thereafter prevented from extending a connec tion or reseizing switches until his receiver is replaced on the switchhook.

Referring now to the drawings, Figs. 1 to 3 may be connected as shown in Fig. 4. shows a calling subscribers line in an exchange and a line finder, the latter in diagrammatic form. Figs. 2 and 3 show a selector-connector circuit originating in the line finder shown in access to a called subscribers line in the exchange as shown in diagrammatic form.

To show the embodiments of the features of this invention in connection with these drawings,

descriptions will be made of a call from a calling subscriber at A, through the calling subscribers line circuit, and the line finder LF, shown in Fig. 1, and the selector-connector 3" shown in Figs. 2 and 3 to a calling subscriber at C, Fig. 3; followed by the operation of these circuits if the calling subscriber fails to dial within a certain time after the seizure of the selector-connector and if the subscriber fails to dial the complete number to establish the connection to the called subscriber, namely, the release of the line finder and the selector-connector under these circumstances. These descriptions in turn will be followed by descriptions of the operations of the circuits whereby the calling subscriber is prevented frc-m seizing another line finder and establishing a connection until he has replaced the receiver on the switchhook, whereby, after the calling subscriber has hung up his receiver at the completion of the conversation with the called subscriber, all of the switches used in the connec- Fig. 1

1 and terminating in brushes which have i tion are released, and whereby, if the called subscriber still has his receiver off the switchhook, his line will immediately seize a set of switches, and how all of these switches are released a certain time interval thereafter provided the called subscriber takes no further action within this interval towards the establishing of a new connection, and how this called subscriber is thereafter prevented from extending a connection until after his receiver is replaced on the switchhook.

Referring now to a call from the subscriber at A to the subscriber at C a circuit is completed when the calling subscriber removes his receiver from the switchhook to cause the operation of line relay 5 from battery, middle winding of this relay, lower inner armature and back contact of relay 6, through the calling subscribers loop back over the upper inner armature and back contact of relay 6, lower winding of relay 5 to ground. Relay 5 in operating connects ground to the start lead I at its lower armature and front contact through contacts of relays 8 and 6 to start the line finder LE to connect its brushes with the terminals of this line circuit and thus connect the calling subscribers line to the selector-connector B. Relay 5 in operating also connects its upper winding from battery through contacts of relays 5 and 8 to the sleeve leads of the line finder. When the line finder has found the line this battery connection to the sleeve lead causes the line finder to stop on the terminals of the line. A ground on the sleeve brush in the line tinder causes the operation of relay 6 from battery, winding of relay 6, contacts and upper winding of relay 5, contacts of relay 8 and the sleeve lead to ground. While the connections for the middle and lower windings of relay 5 from the calling subscriber-s line are opened by the operation of relay 6, this relay 5 will be maintained operated through the circuit over its upper winding by the ground in the line finder until relay 6 has fully operated when relay 5 releases due to the shunting of the battery connection for relay 5 by the closing of the locking circuit for relay 5 at the upper outer armature and front contact of reiay 6. Relay 6 in operating connects the tip and ring conductors from the calling subscribers line to the tip and ring conductors of the line finder and the selector-connector. The ground connection on the sleeve will now be extended to the multiple sleeve connections terminating in selectorconnectors as indicated at III. This ground connection extends through the upper outer armatures and back contacts of relays 8 and B to make these multiple connections busy for incoming calls. The operation of relay 6 will open at this lower armature and back contact the connection to ground for the start lead I.

On the operation of relay 6 the connection over the calling subscriber's loop extended over the tip and ring conductors through the selectorconnector "B causes a circuit to be completed for the operation of relay I05 through the calling subscribers loop over these tip and ring conductors. The tip conductor is connected through contacts of relays I06 and I01. upper winding of relay I05, contacts of relay I98, vertical offnormal contacts I09 to ground. through one winding of the repeating coil H0, the other winding of which is connected to a dial tone source, and the ring conductor is connected through contacts of relays IE8, I06 and It], lower winding of relay I05, contacts of relay I38 to battery. Relay I85 in operating closes a circuit for relay H I. This relay in turn closes a circuit for relay H2 through the upper winding of relay I I2 from ground at the lower inner armature and front contact. Relay III also applies a ground at the upper armature and front contact through contacts of relay I66 over the sleeve conductor H3 to the line finder LF to hold this switch operated. Relay H2 in operating prepares a pulsing path for the vertical magnet H 3 and dial tone is in the meantime transmitted from the tone source through repeating coil I iii to the calling subscriber to indicate that the selectorconnector 'B is ready for the reception of the first series of impulses.

At each interruption of the dial on the sending of the first digit impulses. relay IE5 is released and operates the vertical magnet H4 in series with relay H5, this latter relay remaining operated during the sending of the first digit impulses. The pulsing circuit may be traced from battery through the winding of relay H5, contacts of relay Hi3, winding of vertical magnet in, contacts of relay H2. vertical off-normal contacts WEI to ground at the armature and back contact of relay $05. After the first impulse. the vertical off-normal contacts Iilil shift the pulsing circuit for the vertical magnet and relay H5 through the upper armature and front contact of relay H5 so that at the end of this series of impulses when relay H5 releases, the pulsing circuit may be shifted to the rotary magnet Hi. The shifting of the vertical off-normal contacts Hi9 disconnects the dial tone from the calling ibscribers line. At the end of this series of impulses relay HS releases and the brushes of the selector-connector have been advanced to the desired level in which a called subscribers line is located. On the next digit or series of dial impulses, relay Hi5 releases and operates the rotary magnet H1 and relay H8 in series. This circuit may be traced from battery, contact of relay H9, winding of relay H8, winding of the rotary magnet l H, contacts of relays I24], I22 and H36, upper armature and back contact of relay H5, contacts of relay H2, vertical oibnortaal contacts 89 to ground at the armature and back contact of relay I85. When relay H8 operates this circuitis shifted through the upper armature and front contact of relay H8 independent of the connection through contacts of relay 22. Relay Hi1 remains operated during the pulsing due to its slow release characteristics It should be noted that on the first rotary step the rotary off-normal contacts I25 close a circuit for the operation of relay I22 from battery, windof this relay, rotary oiT-norrnal contacts I25. contacts of relay I29, to ground at contacts of relay H2. Relay I22 closes a locking circuit for itself through its upper inner armature and front contact through contacts of relays I05 and HS to ground at relay H2. Relay I22 in operating opens at its lower outer armature and back contact the original pulsing circuit for rotary magnet HI which is shifted as hereinbefore stated to extend through contacts of relay H8.

At the end of the second series of iniputses. the brushes of the selector-connector 13 wt. be in connection with the terminals of the desired subscribefs line. When this takes place and the line is idle, relay H8 releases and a circuit is thereby completed from battery over the usual cut-off relay in the line of the called subscriber over the sleeve connection through contacts of relay H3, lower winding of relay I20, contacts of relay l2! and contacts of relay H2 to ground. This circuit causes relay I 20 to be partially operated to close a circuit through its upper inner armature and front contact from battery to ground at relay II2 to cause the relay I20 to be fully operated. Relay I20 in operating fully provides a ground for the sleeve circuit at its second upper armature and front contact from contacts of relay [I2 directly to make the called subscribers line busy. Relay I20 also prepares a ringing circuit for the tip and ring conductors to the called subscribers line through the ringing trip relay I23 from a ringing source as hereinafter traced.

This selector-connector B is arranged for party line ringing, and it functions so that regardless of whether the called party is on a single line or on a party line the calling subscriber must operate a ringing code switch R to select a suitable ringing code. This, the subscriber will now proceed to do by sending a code selecting digit to relay I05. For a single line the code I is dialed so that relay I05 will release once. On the release of relay I 05 at this time a circuit is completed for relay I26 and code switch stepping magnet I27 in parallel. The circuit for relay I26 extends from battery through the winding of this relay, contacts of relay I08 to a point I28 and the circuit for the stepping magnet I2"! extends from battery through the winding of this magnet, contacts of relay II I to point I20. From this point on the circuit may be traced through contacts of relay I22, code switch off-normal contacts I30, contacts of relay I22, upper armature and back contact of relay IIB, contacts of relay I06, upper armature and back contact of relay H5, contacts of relay I I2, vertical oif-normal contacts I09 to ground at the armature and back contact of rclay I05. Relay I26, in operating, locks itself over its upper outer armature and front contact to the ground at relay I 05 independent of the ofi-normal contacts I30 and contacts of relay I22. Relay I25 being slow to release remains operated during the sending of the code and then releases. As this code comprises a single impulse, this relay will release when the impulse ceases. A circuit is also completed for the operation of relay H9 from battery, winding of relay H9, contacts of rotary magnet I I1, contacts of relay I26, off-normal contacts I30, contacts of relays I22 and I20, contacts of code switch start interrupter I3I to ground. This circuit is closed when the interrupter-s of code switch R are in a position to permit a full code to be transmitted as is well known in the art. Relay H9 is locked under control of relay I22 to ground at relay H2 independent of interrupter I3I. Relay II9 opens at its lower outer armature and back contact a locking circuit for relay I22 which now releases and closes a circuit for relay H6 from battery, winding of this relay, contacts of relays I22, I20, I08 and I06 to ground at relay III. Relay II5 opens the circuits for the delayed release means to prevent it from functioning as hereinafter described. Relay H9 is in turn released on the release of relay I22.

This first impulse imparts a first step to the stepping magnet I27 which thereupon causes the brushes of the ringing code switch R to connect with the first terminal and thereby close the above mentioned ringing circuit through the windings of the ringing trip relay I23 for ringing of the called subscriber. The circuit may now be traced from the ringing current source I32 through the code interrupter I33, right-hand switch bank, first terminal, and brush of switch R, second upper armature and back contact of relay I22, lower outer armatures and back contacts of relays I23 and I06, lower outer armature and front contact of relay I20 to the ring conductor over the called subscn'bers loop and the ringer in the subscribers telephone set back over the tip conductor, through the upper outer armature and front contact of relay I20, upper outer armatures and back contacts of relays I06 and I23, third upper armature and back contact of relay I22, brush and the left-hand switch bank, first terminal, upper inner armature and back contact of relay I25, upper winding of relay I23 to ground. When the called subscriber C answers relay IE3 is operated sufficiently over this circuit to close its locking winding which causes this relay to operate fully. The locking circuit may be traced from battery lower winding of relay I23 and lower inner armature and front contact to ground at contacts of relay II2. Relay I23 in operating closes at its upper and lower outer armatures and front contacts a tip and ring connection to the condensers I35 and I36 to complete the connection from the calling subscriber to the called subscriber.

This relay I23 also closes a circuit for relay I01 to cause it to operate and to close talking battery connections for the called subscribers circuit. The talking battery for the called subscribers line may be traced from battery through contacts of relay I08, upper winding of relay I01,

contacts of relay I23, contacts of relays I05 and I20 through the tip conductor and the called subscribers loop back over the ring conductor, contacts of relays I20, I06 and I23, through the lower winding of relay I01, contacts of relays I23 and $05 to ground at the upper armature and front contacts of relay III. Relay I01 in operating reverses at the lower armatures and front contacts the connections through relay I05 for the calling subscribers talking battery supply at contacts of relay I08 and ground at vertical 01T- normal contacts of relay I09. The talking circuits for the calling and called subscribers are now completed through the condensers I35 and I36, talking battery for both subscribers being furnished from the same source, at the third upper armature and back contact of relay I08, ground for relay I05 being supplied at the vertical off-normal contacts I09 and ground for re lay I01 being supplied at the upper armature and front contact of relay I I I.

When the calling subscriber disconnects, relays I05, I II and I I2 are released in the order named. The locking circuit for relays I23 and I20 are opened by the release of relay II2 causing these relays to release. The release of relay II2 also restores the code switch R by energizing its release magnet I30 over a circuit closed through the off-normal contacts I30 and the upper outer armature and back contact of relay II2 to ground, this circuit being opened when the code switch returns to normal at the off-normal contact I30. The release of relay I20 removes the ground connection from the sleeve of the called subscribers line and opens the tip and ring connection thus releasing relay I01. Relay I20 also causes the energization of the release magnet I39 of the selector-connector B by closing a circuit for this magnet through its third upper armature and back contact to contacts of relay II 2, ,vertical ofi-normal contacts I09 and the ground at the armature and back contact of relay I05. This circuit is opened at the vertical off-normal contacts when the selector-connector has returned to normal. Relay III in releasing removes the Lid ground from the sleeve connection through the line finder thereby causing this line finder to release and this in turn causes the release of relay 5 in the line circuit of the calling sub-scribers line to return the line circuit to normal.

In order to release the selector-connector and the line finder in case the calling subscriber fails to dial after he has removed the receiver from the hook and the selector-connector B has been seized, an arrangement is provided for causing this release after a certain interval. It will be noted that when relay II2 operates after the seizure of the selector-connector as hereinbefore described, a circuit will be completed for the operation of relay I45 from battery through the winding of this relay, the fifth lower armature and front contact of relay H2 and the upper outer armature and back contact of relay H5 to ground. This relay in turn causes an obvious circuit to be closed for the operation of relay I46. Relay I 48 in operating closes a motor circuit that controls an interrupter as shown at I41. This interrupter in turn will alternately open and close the circuit for the alternate operation and release of relay I48. This controls the stepping circuit for the stepping magnet I49 which controls the switch bank I50 to cause the brush thereof to step over its terminals. After the first step a circuit is closed by the brush of this switch bank I50 from ground through the first terminal to close a circuit for the operation of relay I5I from battery, winding of this relay, lower outer armature and back contact of relay IIS, upper make-before-break contacts of relay I5I, fourth lower armature and front contact of relay II2, the first terminal and brush of bank I50 to ground. Relay I5I operates and closes a locking circuit for itself from battery through its winding, contacts of relay I I6, its upper armature and front contact to ground at the upper armature and front contact of relay H2. Now, if the calling subscriber fails to dial within a certain interval, that is, the time it takes the brush of bank I50 to travel from the first terminal to the seventh terminal, a circuit will be completed from the ground on this brush and the seventh terminal for the Operation of relay 8 in the calling subscribers line circuit. The circuit for this relay may be traced from battery through the lower winding of relay 8 over the C terminal and brush of the line finder, the second lower armature and back contact of relay I08, the lower armature and front contact of relay I5I, through the seventh terminal and brush of bank I50 to ground. Relay 8 in operating closes a locking circuit for itself under control of relay 5 which will operate as hereinafter described. Ground is connected to the sleeve leads of the multiple connections to selector-connectors to make the line busy and relay 8 opens the locking circuit for relay 6. The release of relay 5 disconnects the tip and ring conductors from the line finder circuits and thereby causes the release of the selector-connector in the manner hereinbefore described when the calling subscriber hangs up his receiver. The relay 6 in releasing also connects the tip and ring conductors to the upper and lower windings of relay 5 causing this relay to operate to close the locking circuit for relay 8. The calling subscriber will now be unable to extend the connection through another selector-connector until he has replaced the receiver on the switchhook and again removed it to seize another line finder and selector-connector. When the selector-connector releases the released magnet I39 in operating closes a circuit for the release magnet I52 of the switch I50 to cause it to return to normal. It will be noted that when relay II2 releases relays I45, I46, the interrupter Ml, relay I48 and stepping magnet I49 are deprived of their operating circuits.

From the foregoing it follows that if the calling subscriber does not complete the dialing of the desired subscribers number, the delay release means will operate after the fixed interval to release the connections.

It is evident if the selector-connector is released and the called subscriber still has his recelver off the switchhook this will cause his line to seize a line finder and selector-connector but as he will fail to take any further action the delayed release means will operate to disable his line in the same manner as the calling subscribers line was disabled on the failure to dial.

This system is also arranged for revertive calls, that is, calls between parties on the same line. If the subscriber of a party line decides to make a revertive call, the operation of the system is the same as in the case of a call from a subscriber of a single line such as the subscriber at A up to the point where the selector-connector B finds the terminals of the called line, which in this case would be the same party line over which the call originated. Since relay 5 of this line is already held busy by the line finder LF, a regular busy condition including a busy tone is set up.

This busy condition is identified by the ground on the sleeve terminal of the calling line. Under these circumstances the test relay I2I operates before relay II8 releases over a circuit from battery, winding of relay I2I, contacts of relays I and H8 to ground over the sleeve terminal from the line finder employed. Relay I2I locks to this ground over its own lower outer armature and front contact and make-beforebreak contacts of relays I40 independent of relay II 8. When now relay II8 releases, a circuit is closed from battery, winding of relay II9, contacts of rotary magnet II'I, make-before-break contacts of relay H9, contacts of relays I2I and H8, winding and make-before-break contacts of relay I40 to ground on the sleeve terminal of the called line. Relay I I9 is marginal and does not operate, but relay I40 operates in this circuit. Relay I40 operating provides a locking circuit for itself and the relay I2l through its upper outer armature and front contact to ground at contacts of relay II2. Relay I40 connects the left-hand winding of the busy tone coil I55, to one side of the condenser I35, thereby causing a busy tone to be transmitted through this connection and through contacts of relays I06 and I08 to the calling line.

The calling subscriber now dials the ringing code of the desired party in the same manner as a regular call and the code switch R accordingly causes the code to be transmitted out over the terminals of the party line from the selected interrupter in the usual manner as hereinbefore described and the calling party then replaces his receiver on the switchhook. This causes relay I05 to release to provide a ground connection to the sleeve terminal of the called line. This circuit may be traced as follows: ground through contacts of relay I05, vertical off-normal contacts I09, contacts of relays H2, H5, I05, II8, I22, off-normal contacts I30, contacts of relays I22, I26, II2, sleeve brush and terminal of the called line Relay III then releases and removes the ground from the sleeve terminals to the line finder LF but the ground over the sleeve terminal through the selector-connector from relay I05 extends to the sleeve circuit at I and serves as a substitute ground to hold the line finder and the selector-connector engaged. This ground on the sleeve to the line finder causes the operation of relay I08 from battery, winding of relay I06, contacts of relays I50, II2, III, I00 to ground at the contacts of relay I over the sleeve as hereinbefore traced. Relay I08 in operating opens the ring connection towards the line finder and closes a circuit for relay I20 from battery, upper winding of relay I20, contacts of relays I08, II2, to ground, and relay I20 locks directly to the ground at relay II2. A circuit is closed to ground at relay II6 for the sleeve through contacts of relay I00 to hold the line finder and connector momentarily operated after ringing is tripped. Another circuit is also closed by relay I08 to hold relay II2 operated from battery, upper winding of relay II2, contacts of relays I00 and I23 to ground on the sleeve. Relay I20 in operating closes the tip and ring conductors through to the ringing relay I23 from the called party line and prepares for the transmission of the ringing code by closing the circuit for the momentary operation of relay II9 from the code switch starting interrupter I3I as hereinbefore described to operate relay H6 and release relay I22. The ringing of the called subscriber now takes place as in any other connection for calling a single party line, as hereinbefore described. In this case the code signals may, for example, consist of three impulses from the source I32 controlled by the interrupter I53, with the circuits being otherwise the same as hereinbefore traced for a single party code controlled by interrupter I53. The only exception is that in this case when the called party code is rung out over one side of the line, there are two short ringing impulses transmitted during the silent intervals over the other side of the line. The termination of ringing by these two short ringing impulses when the called subscriber answers informs the calling subscriber when to come in on the connection in case the calling subscribers ringer is located on the opposite side of the line from the called subscribers ringer. These two short ringing impulses are transmitted under control of relay I26, the circuit for which has been transferred by the operation of relay I08 to the impulse lead RS on which a ground momentarily operates this relay twice during the silent intervals. This relay I26 thus causes ringing current from source I32 to be supplied during each silent interval to the tip or ring conductor, depending on the code transmitted. For example, if the code is applied as stated through interrupter I53, it is applied over the ring conductor and the two short impulses are therefore applied over the tip conductor from this source I32, through the upper inner armature and front contact of relay I20, third contact and brush of the left-hand bank of the switch R, contacts of relays I22, I23, I06 and I20 to the tip conductor. These two short impulses will operate all the bells on the tip side of the line so that if the calling subscribers ringer is located on this side, he will know when to answer the call. When the called subscriber answers, the ringing trip relay I23 is operated as usual. In this case, however, due to the operation of relay I03, the ground on the sleeve will be connected over the C terminal and brush of the line finder for the operation of relay 0 from battery, lower winding of relay 8, the C terminal and the brush of the line finder LF, contacts of relays I00 and I23 to ground at the sleeve from contacts of relay I05. Relay 8 in operating opens the locking circuit for the cutoff relay 6 and as the calling or called subscribers, or both, have their receivers off the switchhooks, relay 5 will operate and hold relay 3 operated. The connections through the line finder LF and the selectorconnector B are therefore, due to the release of relay 6, opened and these switches are released in the usual manner as in the case 10 when a calling subscriber fails to dial within a certain interval as hereinbefore described. Talking battery is now applied through the windings of relay 5 and contacts of relay 6. The connection will be released when the subscribers on this line replace their receivers on the switchhook to release relay 5. If the called subscriber fails to answer the call, the calling subscriber must momentarily remove his receiver from the switchhook in order to release the connection. This will operate the ringing trip relay I23 and release will take place as usual.

What is claimed is:

1. In a telephone system, a calling line, a called line, sets of switches, means for establish- 25 ing a connection between said calling line and said called line over a set of switches, means responsive to the calling subscriber replacing his receiver on the switchhook for disconnecting said lines and releasing said switches, means thereafter responsive due to the called subscriber still having his receiver off the switchhook for seizing a set of switches, and means responsive at a predetermined time thereafter if the called subscriber fails to take any further action for releasing said set of switches.

2. In a telephone system, a calling line, a called line, sets of switches, means for establishing a connection between said calling line and said called line over a set of switches, means responsive to the calling subscriber replacing his receiver on the switchhook and for disconnecting said lines and releasing said switches, means thereafter responsive due to the called subscriber still having his receiver ofi the switchhook for seizing a set of switches, and means responsive at a predetermined time thereafter if the called subscriber fails to take any further action for releasing said set of switches and for preventing said called line from reseizing another set of switches until the called subscriber has replaced his receiver on the switchhook.

3. In a telephone system, a calling line, a called line, sets of switches accessible to said lines for establishing a connection between them, means responsive to the calling subscriber removing his receiver from the switchhook for causing a switch of an idle set to be operated to connect the calling line with said set, means responsive to impulses from the calling subscribers line for opcrating switches in the connected set to complete a connection between said lines, a relay associated with the calling line, a timing device common to said sets of switches, means for actuating said timing device when a set of switches is connected to the calling line, means for actuating said relay by said timing device after it has been operated a certain period provided the connection between the two lines has not been completed, means controlled by said relay if operated for releasing actuated switches and for preventing the calling line from being again connected to an idle set of switches as long as the receiver of the calling line remains off the switchhook.

4. In a telephone system, a calling line, sets of switches accessible to said line for establishing connections, means responsive to the calling subscriber removing his receiver from the switchhook for causing a switch of an idle set of switches to be operated to connect the calling line with said set, a relay associated with said line, a timing device common to said sets of switches, means for actuating said timing device when a set of switches is connected to the calling line, a second relay, means for operating said second relay when said timing device is actuated, means operative a certain interval after the actuation of the timing device and in response to the operation of said second relay for actuating said first relay, a third relay, means for actuating said third relay over the calling subscriber's line loop and for releasing said actuated switch in response to the actuation of said first relay, and means controlled by said third relay for maintaining said first relay operated as long as the calling subscribers line loop is maintained.

5. In a telephone system, a calling line, sets of switches each comprising a line finder and a selector, means responsive to the calling subscriber removing his receiver from the switchhook for actuating the line finder of an idle set for associating the calling line terminals with the associated selector, a holding circuit for said line finder closed when said line terminals are associated with said selector, a relay operating through said holding circuit when closed for connecting the calling line conductors with said line terminals to said selector, a timing device common to said sets of switches, means for starting the operation of said timing device when the calling line is extended to said selector, a second relay, means for actuating said second relay by said timing device after it has been operated a certain period provided no impulses have been sent over the calling line to actuate the selector within said period, means operative on the actuation of said second relay for releasing said first relay to disconnect the calling line from its line terminals and for returning said line finder to normal.

6. In a telephone system, a calling subscriber's line, a called subscribers line, sets of switches each comprising a line finder and a selector, means responsive to the calling subscriber removing his receiver from the switchhook for actuating the line finder of an idle set for associating the calling line terminals with the associated selector, a holding circuit for said line finder closed when said line terminals are associated with said selector, a relay operative through said holding circuit when closed for connecting the calling line conductors with said line terminals to said selector, means for actuating said selector over the calling line conductors to extend the calling line conductors to said called sub-- seribers line, a timing device common to said sets of switches, means for starting the operation or" said timing device when the calling line is extended to said selector, a second relay, means for actuating said second relay by said timing device after it has been operated a certain period provided said selector has not been actuated to complete the connection to the called subscribers line within said period, means operated on the actuation of said second relay for releasing said first relay to disconnect the calling line from its line terminals and for returning said line finder and selector to normal.

7 In a telephone system, a calling line, a called line, sets of switches, means for establishing a connection between said calling line and said called line over a set of switches, means responsive to the calling subscriber replacing his receiver on the switohhook for disconnecting said lines and releasing said switches, means thereafter responsive due to the called subscriber still having his receiver of? the switchhook for causing a switch of an idle set of switches to operate to connect said called line with an idle set of 10 switches, and means responsive at a predetermined time after the connection of the called line to said switch for disconnecting it and restoring it to normal if the called subscriber fails to take any action towards the establishing of a connection through said appropriated set of switches.

8. In a telephone system, a calling line, a called line, sets of switches, means for establishing a connection between said lines over a set of switches, means responsive to the calling subscriber replacing his receiver on the switchhook for disconnecting said lines, means thereafter responsive to the called subscribers receiver being ofi the switchhook for causing a switch of an 26 idle set of switches to be operated to connect the called line with said set, a relay associated with said called line, a timing device common to said sets of switches, means for actuating said timing device as soon as the called line is 30 connected to a set of switches, means for actuating said relay by said timing device after it has been operated a certain period, and means controlled by said relay when operated for releasing the said actuated switch to normal for preventing the called line from being again connected to an idle set of switches as long as the receiver of said called line remains off the hook.

9, In a telephone system a calling line, a called line, sets of switches accessible to said lines for establishing a connection between them, means responsive to the calling subscriber removing his receiver from the switchhook for causing a switch of an idle set to be operated to connect the calling line with said set, means responsive to impulses from the calling subscribers line for operating switches in the connected set to complete a connection between said lines, a relay associated with the calling line, a timing device common to said sets of switches, means for actuating said timing device when a set of switches is connected to the calling line, means for actuating said relay by said timing device after it has been operated a certain period it no impulses have been received from the calling line for completing the connections between the two lines, means controlled by said relay if operated for releasing the switch connected to the calling line and for preventing the calling line from being again connected to an idle set of switches as long as the receiver of the calling line remains oif the switchhook.

10. In a telephone system, a calling line, a called line, sets of switches accessible to said lines for establishing a connection between them, means responsive to said calling subscriber removing his receiver from the switchhook for causing a switch of an idle set to be operated to connect the calling line with said set, means responsive to impulses from the calling subscriber's line for operating switches in the connected set to complete a connection between said lines, a relay associated with the calling line, a timing device common to said sets of switches, means for actuating said timing device when a set of switches is connected to the calling line, means for actuating said relay by said timing switch after it has been operated a certain period if impulses have been received from the calling line but not sufficient for the completion of a connec- 5 tion between the two lines, and means controlled by said relay if operated for releasing actuated switches and for preventing the calling line from being again connected to an idle set of switches as long as the receiver of the calling line remains oil the switchhook.

ALFRED E. HAGUE. JOHN B. DRAPER. 

